Method for guaranteeing the authenticity of documents

ABSTRACT

What are proposed are a method and a system for guaranteeing the authenticity or checking the authenticity of documents, in particular banknotes or the like, which each have a substrate ( 1 ) with specific substrate features ( 2 ), an image of the substrate being recorded before a document is issued and the image data obtained in the process being stored in a manner assigned to document data, in order to keep these data ready for possible later comparison enquiries concerning the authenticity of an issued document.

DESCRIPTION

The invention relates to a method for guaranteeing the authenticity ofdocuments, in particular banknotes, securities, passes, entrance cards,credit cards, smart cards or the like, which each have a substrate withspecific substrate features that can be detected optically or in aspatially resolved manner, and which are provided with document data.

Despite intensive endeavors to configure security documents, inparticular banknotes, in such a way that deceptive imitations are as faras possible precluded, counterfeiters are nevertheless successful againand again in putting counterfeit documents into circulation. Cases ofbanknote forgeries have become known in which not only the printedpattern of banknotes has been reproduced almost exactly, but also thesubstrate used for the banknotes, that is to say the special securitypaper. Such examples have shown that money counterfeiters are able andalso prepared to expend a high outlay in order to make their counterfeitproducts appear as authentic as possible.

In the course of the endeavors to make documents as forgery-proof aspossible, considerations have already been formulated for preparing thesubstrate material for security documents such that the authenticity ofa document comprising such a substrate material can be checked by meansof special tests which, however, are simple to carry out. One example ofsuch considerations is set forth in U.S. Pat. No. 6,054,021. Inaccordance with U.S. Pat. No. 6,054,021, fluorescent cellulosic fibersare admixed with the paper pulp during substrate production for asecurity paper, said fibers being distributed stochastically in thepaper mass. A document produced from a paper mass prepared in this waythus has a random distribution of fluorescent cellulosic fibers in itssubstrate, which stand out from their surroundings with high opticalcontrast under fluorescence conditions. In order to check theauthenticity, such documents are exposed to a radiation that stimulatesthe fluorescence of the fibers, e.g. UV radiation. If no fluorescentfibers appear in this case, then the document is qualified ascounterfeit.

It is not possible to rule out the situation wherein documentcounterfeiters expend such a high outlay that, in conformity to theguaranteeing of authenticity described above, they likewise usesubstrates with fluorescent particles or imitate these substrates.

The invention is based on the object of specifying an improved methodfor guaranteeing the authenticity of documents which makes itsubstantially more difficult to counterfeit the relevant documents.

In the method according to the invention for guaranteeing theauthenticity of documents, in particular banknotes, securities, passes,entrance cards, credit cards or the like, which each have a substratewith specific substrate features than can be detected in a spatiallyresolved manner, and which are provided with document data, a respectivedocument, before being issued, is. analyzed in a spatially resolvedmanner altogether or partly—and a data record with information about thearrangement and/or fashioning of specific substrate features of thedocument is generated in the process, the data of said data record ordata derived therefrom being stored in a database together with or in amanner assigned to document data of the relevant document, in order tokeep them ready for later authentication enquiries.

The specific substrate features under consideration here are, inparticular, structural details of the substrate, which is preferablyprepared to form a sheet, said details having a stochastic orquasi-stochastic form design or distribution in or on the substrate.Special structural features may be involved in this case, by way ofexample, such as, for instance fiber structural features, microstructurestructural features, foreign body inclusion features or the like, whichdo not significantly change their appearance image—detectable byspatially selective analysis—even in the course of wearing treatment ofthe relevant document in later use, since, during a later authenticitycheck, a relevant document is intended to be recognizable (at leastalso) on account of such specific substrate features.

Appropriate substrate materials are, in particular, paper, cardboard,plastic, textile, metal, etc.

The spatially resolved analysis of the document is preferably effectedoptically by an imaging method, the data obtained in the processcontaining image information about the region of the document underconsideration. These image data and/or data derived therefrom in thecourse of data compression, coding or according to some otherpredetermined data processing process are stored in the database forauthentication purposes. The spatially resolved analysis particularlypreferably consists in the respective document or a particular regionthereof being optically scanned by means of a scanner device or beingphotographed or, if appropriate, videographed by means of a digitalcamera.

In accordance with one variant of the method according to the invention,both sides of a document are optically acquired completely or partly, inorder to obtain data for the description of the substrate features.Given a sufficient thickness of a document, it may furthermore beprovided that the peripheral region or the edge region is also orexclusively included in the optical acquisition.

Document data are customarily provided on the respective substrate inthe form of graphical patterns, markings, image elements and/orinscriptions, etc. However, in the case of documents with relevantstorage media, document data may also or alternatively be stored inmemory chips, magnetic strips, etc.

General document data such as specifications of value, printing imageelements, document manufacturer indications or the like are normallyembodied identically for a relatively large number of documents of adocument type. Specific document data such as serial numbers, individualmarkings, etc. are normally different for all documents of a documenttype and are therefore suitable as an assignment criterion in thestorage of the data obtained during the spatially selective analysis ofa document (substrate feature information).

By virtue of the electronic storage “of an image” of the substratestructural details that are specific to each document, because they areformed or distributed under quasi-random conditions, in a mannerassigned to specific document data which identify the document as such,a comparison data record specific to each document is thus createdbefore the document is issued by the document manufacturer or, ifappropriate, a separate authorization entity, said comparison datarecord being kept ready for possible later comparison enquiriesconcerning the authenticity of an issued document.

The method according to the invention is preferably employed in the caseof documents in which the structural details are formed by opticallyprominent small particles of the substrate or by small extraneousinclusions in the substrate base material. Said particles may be e.g.photochromic fibers, fluorescent fibers, or fibers having some otherspecific optical properties, which fibers can be represented with highcontrast against the optical background of the substrate base mass, andare preferably incorporated into the substrate mass. As alreadymentioned, document substrates with fluorescent fibers are known, forexample from U.S. Pat. No. 6,054,021.

Quite generally, the method according to the invention should relate tothose documents in which the optically prominent particles have specificoptical properties, in particular a different coloration,wavelength-selective absorption, fluorescence, phosphorescence,photochromic properties, polarization-sensitive properties and/orviewing-angle-dependent properties, with respect to their substratesurroundings.

As already mentioned, many types of documents, for instance banknotes,are identified by individualizing document data provided on thedocument, e.g. by running serial numbers. When guaranteeing theauthenticity of such documents, in particular, the method according tothe present invention should be carried out in such a way that suchspecific document data are stored in combination with the substratefeature image data or, if appropriate, data derived therefrom. Duringimage data recording, it is possible to carry out for this purpose asimultaneous optical acquisition of the document data provided on therelevant document specimen and of the structural detail image data, forexample by means of joint scanning. The data record obtained should thencontain an unambiguous spatial assignment of specific document data andspecific substrate features.

The document data may e.g. be printed on the respective substrate bymeans of a fluorescent ink. Assuming that the substrate structuraldetails to be acquired, for example statistically distributed structuralfibers, also fluoresce, then it is possible to carry out thesimultaneous imaginal acquisition of the specific substrate structuralfeatures and of the specific document data under fluorescenceconditions.

Preferably, at least some of the relevant substrate features, inparticular extraneous inclusions embedded in the substrate base mass,and/or possible markings, printed patterns or document data imprints onthe substrate should contain photochromic material, preferablybiological material, such as e.g. chemically or genetically modifiedbacteriorhodopsin or a plurality of bacteriorhodopsins which havedifferent properties, e.g. different absorption maxima, differentfluorescence properties, different light sensitivities or differentkinetics for returning to the initial state. The specific opticalproperties of the photochromic material can be utilized in guaranteeingthe authenticity and checking the authenticity of documents.

In the case of bacteriorhodopsin, it is possible e.g. to carry out afirst image data acquisition with the document being illuminated withyellow light, and then to carry out a second image data acquisition withthe document being illuminated with blue light. Subtracting the data ofthe first image data acquisition from the data of the second image dataacquisition (or vice versa) yields image data highlighting e.g. thoselocations of the document which contain bacteriorhodopsin.

Even though a preferred embodiment of the method provides forguaranteeing the authenticity of such documents in which the opticallyprominent particles are incorporated into the substrate base mass,another application variant of the method according to the invention mayprovide for the need to guarantee documents in which a material withspecific structural details that can be detected in a spatially resolvedmanner or optically is applied to the document substrate. This appliedmaterial may be e.g. a color, ink or a coating with prominent particles,e.g. mica laminae or the like. Printing such a color, ink or coatingliquid onto a relevant document substrate then results in a randomdistribution of these particles on a defined area, said particlesrepresenting, in the sense of the present application, substratefeatures which are to be acquired in a spatially resolved manneraccording to the method of the present invention.

There are document types which do not require an identification thatindividualizes each individual document specimen in the sense ofconsecutive numbering, for example a set of entrance cards for an eventwhich are not provided with serial numbers. With regard to guaranteeingthe authenticity in the context of the method according to theinvention, it may suffice for an image of the specific structuraldetails from each document specimen to be stored with the note that theimage data are assigned to a particular document type. Consequently, insuch a case as well, the image data are stored in a database in a mannerassigned to document data, the note of a relevant document typecorresponding to such document data which, in this special case, areidentical for all document specimens and need not necessarily be printedon the document.

For checking the authenticity of a document, the document is analyzed ina spatially resolved manner by means of a checking device in order togenerate a data record with information about the arrangement and/orfashioning of individual substrate features of the document. Thespatially resolved analysis is preferably effected optically by means ofan imaging method, e.g. by scanning, the data obtained in this casecontaining image information about the region of the document underconsideration. The image data determined at the document to be checkedor, if appropriate, data derived therefrom are then compared with thedata archived in the database. If it is ascertained in this case that adata record with corresponding authentication data exists for thedocument in the database, then an acknowledgement confirming theauthenticity of the document can be output from the database to thechecking entity. If there is no correspondence between the data to becompared with one another which is adequate in the context of a possibleerror tolerance, then this is an indication that the checked document iscounterfeit.

The digital storage of the image data in the archiving database may becarried out in a conventional manner by means of an electronic dataprocessing system which is programmed in accordance with the specificobjective. The data obtained during the image recording should besubjected to data compression for reasons of economy in respect ofstorage space, the compressed data then being stored in a mannerassigned to the document data, which, if appropriate, are likewisecompressed. Suitable data compression programs are available and formpart of the prior art, so that they need not be explained in any greaterdetail here.

In accordance with a procedure according to the invention, the databasewith the stored image data of the substrate features and the assigneddocument data is managed and kept secure only by one or by a smallnumber of authentication entities authorized to do so.

The data exchange, that is to say the communication of the data from arelevant checking unit, set up for acquiring the image data from adocument, to the data processing system controlling the archivedatabase, may take place e.g. online by remote data transmission, in thesame way as the acknowledgement from the data processing system thatperforms the data comparison. The remote data transmission may beeffected by radio, for instance mobile radio, or in line-conductedfashion.

A situation in which a data exchange between a document checking entityand the authentication entity takes place by means of the transfer ofdata carriers, e.g. CD-ROMs or DVD-ROMs, is also conceivable. Takingaccount of the security measures that are offered, it is possible forthe data exchange also to be handled via the Internet, for example.

In accordance with a further method variant according to the invention,an algorithm for calculating at least one check code value assigned tothe document specimen is applied at least to a portion of the image dataof a respective document or to data derived therefrom and the documentspecimen is then provided with a marking representing the check codevalue before the document is issued.

Preferably, only a portion of the recorded data record, e.g. a portioncorresponding to a particular image area on the document, is used forcalculating the check code value.

In the course of subsequently checking the authenticity of a documentprepared with a check code value, said document is acquired imaginallyby a checking unit in order to generate a corresponding data record,which is then processed using the special check code calculationalgorithm. If the check code value that is determined in this casecorresponds to the check code value found on the document, then this isto be assessed as a sign of the authenticity of the document. If thecheck code value determined in the course of checking the document doesnot correspond to the check code value found in the form of a marking onthe document, then this is an indication that the checked document iscounterfeit.

The check code value calculation algorithm, that is to say theencryption mechanism, must be safeguarded such that it is not accessibleto unauthorized entities and thus cannot be verified by potentialcounterfeiters.

Checking devices or the image-acquiring components thereof may beintegrated e.g. in automatic point-of-sale machines in order to checkthe authenticity of banknotes supplied to the automatic point-of-salemachine.

The invention also relates to a document with a marking which representsa check code which depends on specific substrate features or structuraldetails of the document and has been determined by application of acheck code value calculation algorithm to image data of relevantstructural details. Instead of or in addition to such a marking, acorresponding check code may also, if appropriate, be stored in a memorychip, magnetic strip or the like.

The invention furthermore relates to a document in whichsignal-conducting, preferably light-guiding, fibers or the like areembedded in a quasi-random spatial arrangement in a substrate base mass,so that at least some fibers run from one area of the document toanother area of the document and can take effect in signal-transmittingfashion.

The invention is explained in more detail below with reference to thefigures.

FIG. 1 shows a fictitious document, e.g. a banknote, as an example of aspecific specimen of a large number of documents whose authenticity canbe ensured with a high degree of certainty by the method of the presentinvention.

FIG. 2 shows a schematic illustration of a system comprising a centraldevice for guaranteeing the authenticity of documents and decentralizedchecking devices for checking relevant documents.

FIG. 3 a and FIG. 3 b show the document from FIG. 1 in the state beforeand after an authenticity check.

FIG. 4 and FIG. 5 show a substrate material with embedded light-guidingfibers in order to elucidate a further aspect of the invention.

The document 1 in accordance with FIG. 1 has a paper substrate, intowhich are incorporated in an arbitrary or random distribution, smallfibers 2 that are optically prominent with respect to the substrate basemass. The case of the example involves fluorescent fibers whosefluorescence can be stimulated by irradiation with a UV stimulationlight. The fibers 2 were added to the paper pulp, so that they were ableto be distributed stochastically during the further processing of thepaper pulp to form the sheetlike substrate. What is thus achieved isthat each document specimen 1 produced in this way has a random andspecific distribution of the optically prominent fibers 2 in thesubstrate. Preferably, the fibers are located in the document such thatthey can be made visible or are visible on both sides of the document.

The document in accordance with FIG. 1 has a value marking printed on at3. 4 designates an indication of authenticatability, that is to say anindication that the document can be authenticated according to thepresent method, and a manufacturer identification marking on thesubstrate, which can be used to identify. the authorized manufacturer ofthe document or the entity authorized for authenticating the document.

At 5, FIG. 1 illustrates a specific serial number of the document, whichis printed on the substrate 1.

At 6, FIG. 1 shows a printed image which is identical for all thespecimens of the document type under consideration.

At 7, FIG. 1 illustrates an authentication change field, which will bediscussed below.

In the schematic illustration in accordance with FIG. 2, the border 10symbolizes a protected area in which banknotes 1 in accordance withFIG. 1. are manufactured by an authorized manufacturer. One of the lastproduction stages in the manufacture of banknotes is sketched in thearea 10, in which case paper sheets 12 comprising banknotes 1 that havealready been printed but have not yet been separated by cutting aremoved on a conveyor line 14 in the direction of a cutting machine (notshown). An automatic image recording device, preferably scanner device16, is provided at the conveyor line 14, said device being set up foroptically scanning the banknote paper sheets 12, which are movedintermittently on the conveyor line 14 in the direction of the arrow 15,on both sides in regions, in order to acquire an image of each banknote1. The correct positioning of the banknotes 1 relative to the scanner 16is effected automatically by means of the control of the drive means ofthe conveyor line 14, so that each banknote 1 which passes the scannerdevice 16 on the way along the conveyor line 14 is acquired optically.Since an image of the distribution of the fluorescent fibers 2 is alsointended to be recorded during the optical acquisition, the respectivescanning operation is effected under the conditions of fluorescence ofsaid fibers 2, the fluorescence stimulation being effected byirradiation by means of a UV light source (not shown). The serial number5 is also acquired during the image recording of each banknote, whichserial number can preferably be made visible as a fluorescent marking.The image data recorded by the scanner device 16 are accepted by a dataprocessing system 18, which compresses the image data according to adata compression program and stores them in the compressed form in anarchive database 21 of the archive memory 20. In this case, the imagedata assigned to the individual banknotes 1 are stored in the archivedatabase 21 in a manner assigned- to the respective serial numbers 5.After being completed, the banknotes 1 are put into circulation by anentity authorized to do so.

The archive database 21 is kept secure by an authorized entity, e.g. bythe manufacturer of the banknotes 1. However, it is available forcomparison enquiries concerning the authenticity of banknotes incirculation.

The checking of the authenticity of a banknote 1 using the archivedatabase may take place in the following manner. The banknote 1 to bechecked is fed to a checking unit 22, which has an image recordingdevice 24 for recording image data of. the banknote which isrespectively to be checked. The image recording device 24 may containe.g. an optical scanner or a digital camera. In the case of the example,the image recording is effected in conjunction with UV exposure in orderto create fluorescence- conditions for the banknote to be checked.

The image data obtained during the image recording of a banknote to bechecked can then be transmitted to the data processing device 18 in theprotected area 10 via a remote data transmission connection, for thepurpose of a comparison enquiry. According to the serial number 5 of thebanknote to be checked, the data processing device 18 then accesses thearchive database 21 in order to compare the image data stored for theserial number in the archive database 21 with the received image data.If this comparison reveals correspondence in the context of a particularerror tolerance, then the data processing device 18 sends anacknowledgement to the relevant checking unit 22 in order to confirm theauthenticity of the checked banknote 1. Otherwise, an acknowledgement iseffected from the data processing device 18 to the checking unit 22 withthe information that the authenticity of the checked banknote is notconfirmed.

The decentralized checking units 22 may be integrated for example inautomatic point-of-sale machines/automatic cash machines or the like.

It has been assumed hitherto with reference to FIG. 2 that the archivedatabase 21 is kept secure by an authorized entity in the protected areaand that only results of comparison enquiries are communicated from thedata processing device 18 to the respective enquiry device 22.

In accordance with one variant of the method for guaranteeingauthenticity according to the invention, it may be provided that copiesof the archive database 21 are created and communicated to decentralizedauthentication entities. These decentralized authentication entities canthen likewise process comparison enquiries.

In accordance with a further variant of the authenticity guaranteeingsystem according to the invention, the data processing device 18determines a check code value for each individual banknote 1 on thebasis of the image data originally acquired by means of the imagerecording device. The check code value is calculated according to aprotected algorithm which is applied to the respective image data of thebanknotes 1. Since the banknotes differ on account of the randomdistribution of the fluorescent security fibers 2 in the substrate andthese differences are manifested in the image data, the check codecalculation algorithm leads to different check code values for theindividual banknotes 1.

FIG. 2 indicates by dashed lines a printing mechanism 28 assigned to thevariant of the authenticity guaranteeing system being discussed in thepresent case, which printing mechanism is connected downstream of theimage recording device 16 and is set up for printing onto the banknotes1 the check code values respectively determined by means of the dataprocessing device 18, to be precise preferably by means of a fluorescentor photochromic printing ink. The banknotes 1 prepared in this way canthen be put into circulation after being completed.

In a departure from the situation described above with reference to FIG.2, a check of such a banknote which is based only on the check codevalue does not require a data exchange between checking unit 22 and thearchive database management 18. The checking units 22 contain a computeror communicate with a computer which calculates a check code value fromthe image data acquired by means of the image recording device 24 duringthe checking of a banknote 1. The check code value of the banknote 1calculated during the check is then compared with the check code valueprinted on the banknote 1 by the checking unit 22. In the case where theprinted-on check code value 7 corresponds to the check code valuecalculated in a decentralized manner during the check, the checking unit22- confirms the authenticity of the banknote 1. If correspondence ofthe check code value 7 is not ascertained, then this is assessed as anindication that the checked banknote 1 is counterfeit.

The image data acquisition and/or image data evaluation for the originalarchiving and/or during the later checking of documents may be withreference to one or, if appropriate, a plurality of partial areas of thedocument. The position of such a partial area on the documents may besubject to secrecy, so that only authorized entities and in particularthe authentication entity know it. In particular, it may be providedthat the partial area which is to be taken into consideration for acheck of a document is determined at the current time for a respectivechecking operation by the authentication entity and is communicated tothe checking entity or the checking unit by data transmission only whenthe checking operation is initiated. If authentication is not possibleowing e.g. to severe contamination of the partial area, a data recordconcerning another partial area can be requested by remote datatransmission from the authentication entity before the document isrejected as not authenticatable, withdrawn or destroyed by the checkingunit. Restricting the check to partial areas limits the volume of datato be acquired, to be transmitted and to be checked to a comparativelysmall value.

The image data acquisition and/or image data evaluation may furthermorebe effected spectrally selectively. For this purpose it may be providedthat varicoloured fluorescent particles or fibres are distributed in thesubstrate. The spectral ranges taken into account in the evaluationcould likewise be kept secret and, if appropriate, be changed fromchecking operation to checking operation.

A further embodiment variant of interest of the method according to theinvention is quite generally characterized by the fact that a specificchange in the document initiated and documented by the authenticationentity is performed during a respective checking operation. During thenext checking operation the authentication entity expects the presenceof the changed feature in order to qualify the document as genuine. Thechange in the document corresponds to the addition or variation of afeature which documents the authentication operation. The possibilitiesfor a specific change in a document in the sense explained above aremanifold. Thus, by way of example, individual substrate features may bechanged irreversibly by means of a laser. In the simplest case, it ispossible to produce a small burn on the document or a small hole in thedocument by means of laser radiation. Moreover, it is possible for asmall location on the document to be printed with ink or metal vapor,e.g. by means of a printer, for instance a thermosublimation printer. Ifthe document is printed with fluorescent dyes, then the latter can beirreversibly bleached with intensive laser light in order to bring aboutthe targeted change.

If documents are provided with memory chips or, if appropriate, magneticstrips, etc., such a specific change may also consist in storing a checkcode in the memory chip or magnetic strip, the presence of which checkcode is among the preconditions for authentication during a next checkof the document.

In the context of the present application, independent importance isalso accorded to the aspect of the specific change in the documentperformed each time a document is checked, and the checking for thepresence of the changed feature during a next checking operation of thedocument.

This aspect of the invention yields a very high degree of protectionagainst forgery. Even if counterfeiters succeed in producing exactcopies of an issued document, at most one specimen of these copies candeceive the authenticity checking operation since, after all, the firstspecimen checked, after the check, has the changed or added feature and,upon a next enquiry, the authentication entity expects the said changedfeature at the relevant document in order to confirm authenticity.

FIGS. 3 a and 3 b illustrate a document of the type shown in FIG. 1before (FIG. 3 a) and after (FIG. 3 b ) a checking operation with aspecific change in the document. The document 1 has an authenticationchange field in the form of a pixel matrix 8. In the event of a check ofthe document 1 in FIG. 3 a by means of a checking unit 22 in accordancewith FIG. 2, the pixels P1 and P2 have been changed, so that thedocument 1 has thus obtained a new identity having the features of FIG.3 b . The pixel change has been brought about by irreversibly changing adye applied on the field 8 at the relevant locations P1 and P2 by meansof laser radiation of a laser 26 integrated in the relevant checkingunit 22, for example by bleaching a fluorescent dye. The informationregarding the concrete locations of the authentication change field 8 atwhich pixel changes are intended to be brought about has beencommunicated to the checking unit 22 or the controller of the laser 26integrated therein in the course of the relevant checking operation bymeans of bidirectional data transmission between checking unit 22 andauthentication entity 10. The change in the document 1 is noted in thearchiving database 21 of the authentication entity 10 in order to beable to take it into account as an authenticity criterion in the case ofa subsequent check of the same document 1.

A further aspect of the invention is explained below with reference toFIGS. 4 and 5. FIG. 4 shows a document substrate 101 cut to size in theform of a card, for instance a credit card or the like. The card 101comprises a plastic as substrate base material and light-guiding fibers102 which permeate the substrate base material or are embedded therein.The distribution and the positioning of the light-guiding fibers 102 inthe substrate 101 are arbitrary and have arisen on account of astochastic or quasi-stochastic process during the production of thesubstrate. In the case of the example, the light-guiding fibers wereadded to the still liquid plastic of the substrate base mass in adisordered manner prior to curing and the plastic with embeddedlight-guiding fibers was shaped into larger plates. FIG. 5 illustrates aregion from such a plate, depicted in cutaway fashion, after the curingof the plastic. The card 101 illustrated in FIG. 4 was cut out of thisplate. The card contour is illustrated by dashed lines in FIG. 5.

On account of the quasi-stochastic positioning of the fibers 102 withinthe substrate 101, the distribution of the fiber ends at the individualcard sides is also random. It will equally be random what fiber reachesfrom one narrow side 104 to one of the other narrow sides 104 of thecard 101 in order to be able to transport light radiated in at onenarrow side toward the other narrow side. Consequently, whenguaranteeing the authenticity in the context of the invention, the lightpattern arising at one or at a plurality of narrow sides 104 of the carddepending on the illumination of one or a plurality of the other narrowsides 104 can be optically acquired in a spatially resolved manner inorder to generate a data record whose data or, if appropriate, dataderived therefrom are stored in an archived database in order to keepthem ready for later authentication enquiries. In the event of a laterauthenticity check of a credit card, smart card or the like which isproduced on the basis of the substrate 101, the light pattern is thencorrespondingly acquired in a spatially resolved manner at one or, ifappropriate, a plurality of narrow sides 104 in a manner dependent onthe light radiated into one or a plurality of the other narrow sides 104of the card 101, in order to obtain data which are then to be comparedwith the data stored in the archive database and consequently permit anauthenticity check.

In the example shown, it has been assumed that the light-guiding fibers102 extend essentially in the plane of the card 101 and that thespatially resolved analysis is restricted to the narrow sides 104. Inalternative embodiments, it may be provided that the surface sides 106are additionally or exclusively acquired during the spatially resolvedanalysis of the substrate 101. In this case, it may be provided thatlight-guiding fibers 102 also run distinctly transversely with respectto the card plane.

The aspect of embedding signal-transmitting fibers with quasi-randompositioning within a substrate base material for the purpose ofguaranteeing authenticity, which aspect was discussed above withreference to FIGS. 4 and 5, is, in the context of the invention, notjust restricted to card formats, but can also be applied to other two-or three-dimensional formats of documents or articles of value, etc. Thesubstrate base material, preferably plastic, may be transparent ornontransparent.

Instead of light-guiding fibers, electrically conductive wires could beembedded, in which case, during the evaluation, it is then necessary toemploy an electrical or electronic method for determining the positionof the wire ends. In the context of the invention, the same principlemay generally be applied to articles or housings of articles, forexample of electronic chips or the like, or it can be applied topackaging materials.

1. A method for guaranteeing the authenticity of documents which eachhave a substrate with substrate features (2) specific to each individualdocument and are provided with document data, a respective document,before being issued, being analyzed in a spatially resolved manneraltogether or partly—and a data record with information about thearrangement and/or fashioning of specific substrate features of thedocument being generated in the process, the data of said data record ordata derived therefrom being stored in a database together with or in amanner assigned to document data of the relevant document, in order tokeep them ready for later authentication enquiries, each authenticitycheck of an issued document involving performing a specific change in afeature of the document, the presence of the changed feature being aprerequisite for authentication of the document in the event of a nextauthenticity check.
 2. The method for guaranteeing authenticity asclaimed in claim 1, the spatially resolved analysis being carried outoptically using a method that generates image data, in particular bysingle-sided or two-sided scanning of the document.
 3. The method forguaranteeing authenticity as claimed in claim 1, the specific substratefeatures being formed by stochastically or quasi-stochasticallydistributed, optically prominent particles (2), in particular fibers. 4.The method for guaranteeing authenticity as claimed in claim 3, theoptically prominent particles (2) being incorporated into the substratemass.
 5. The method for guaranteeing authenticity as claimed in claim 3,the optically prominent particles (2) adhering to the substrate surface.6. The method as claimed in claim 5, the optically prominent particleshaving been applied to the substrate surface as admixtures to a printingink or ink.
 7. The method for guaranteeing the authenticity of documentsas claimed in claim 1, the optically prominent particles (2) havingspecific optical properties, in particular fluorescent, phosphorescent,photochromic, polarization-sensitive or viewing-angle-dependent opticalproperties, and the spatially resolved optical analysis of the relevantdocument being carried out utilizing the specific optical properties ofthe particles (2).
 8. The method for guaranteeing the authenticity ofdocuments as claimed in claim 1, at least some substrate features and/ordocument data features containing a photochromic material, in particulara bacteriorhodopsin or a plurality of bacteriorhodopsins which havedifferent optical properties.
 9. The method for guaranteeingauthenticity as claimed in claim 1, the document data comprising datathat individualize the relevant document, in particular serial numberdata.
 10. The method for guaranteeing authenticity as claimed in claim1, the document data comprising information about the documentmanufacturer and/or about an entity authorized for authentication and/orabout the authentication possibility and/or for identification of thedocument owner and/or about the intended use of the document and/orabout the value of the document.
 11. The method for guaranteeingauthenticity as claimed in claim 1, document data being provided on thesubstrate in the form of graphical representations, letters, numbers orthe like.
 12. The method for guaranteeing authenticity as claimed inclaim 1, document data being stored in a memory chip and/or on amagnetic strip of the document.
 13. The method for guaranteeingauthenticity as claimed in claim 1, an algorithm for calculating atleast one check code value assigned to the respective document specimenbeing applied at least to a portion of the image data of a respectivedocument or to data derived therefrom and the document specimen beingprovided with a marking that represents the check code value. 14.(Cancelled)
 15. (Cancelled)
 16. A document in which signal-conducting,preferably light-guiding fibers or the like are embedded in aquasi-random spatial arrangement in a substrate base mass, so that atleast some fibers run from one area of the document to another area ofthe document and can take effect in signal-transmitting, in particularlight-guiding, fashion.